Support for multiple body parts

app/src/main/java/eu/faircode/email/MessageHelper.java

@@ -1221,41 +1221,50 @@ public class MessageHelper {
     }
 
     class MessageParts {
-        private Part plain = null;
-        private Part html = null;
+        private List<Part> plain = new ArrayList<>();
+        private List<Part> html = new ArrayList<>();
         private List<AttachmentPart> attachments = new ArrayList<>();
         private ArrayList<String> warnings = new ArrayList<>();
 
         Boolean isPlainOnly() {
-            if (plain == null && html == null)
+            if (plain.size() + html.size() == 0)
                 return null;
-            return (html == null);
+            return (html.size() == 0);
         }
 
         Long getBodySize() throws MessagingException {
-            Part part = (html == null ? plain : html);
-            if (part == null)
-                return null;
-            int size = part.getSize();
-            if (size < 0)
-                return null;
+            Long size = null;
+
+            List<Part> all = new ArrayList<>();
+            all.addAll(plain);
+            all.addAll(html);
+            for (Part p : all) {
+                int s = p.getSize();
+                if (s >= 0)
+                    if (size == null)
+                        size = (long) s;
                     else
-                return (long) size;
+                        size += (long) s;
+            }
+            return size;
         }
 
         String getHtml(Context context) throws MessagingException, IOException {
-            if (plain == null && html == null) {
+            if (plain.size() + html.size() == 0) {
                 Log.i("No body part");
                 return null;
             }
 
-            String result;
-            Part part = (html == null ? plain : html);
+            StringBuilder sb = new StringBuilder();
+
+            for (Part part : html.size() > 0 ? html : plain) {
                 if (part.getSize() > MAX_MESSAGE_SIZE) {
                     warnings.add(context.getString(R.string.title_insufficient_memory));
                     return null;
                 }
 
+                String result;
+
                 try {
                     Object content = part.getContent();
                     Log.i("Content class=" + (content == null ? null : content.getClass().getName()));
@@ -1289,10 +1298,13 @@ public class MessageHelper {
                     Log.e(ex);
                 }
 
-            if (part == plain)
+                if (part.isMimeType("text/plain"))
                     result = "<div>" + HtmlHelper.formatPre(result) + "</div>";
 
-            return result;
+                sb.append(result);
+            }
+
+            return sb.toString();
         }
 
         List<AttachmentPart> getAttachmentParts() {
@@ -1637,14 +1649,11 @@ public class MessageHelper {
                         contentType = new ContentType(Helper.guessMimeType(filename));
                 }
 
-                if (!Part.ATTACHMENT.equalsIgnoreCase(disposition) &&
-                        TextUtils.isEmpty(filename) &&
-                        ((parts.plain == null && "text/plain".equalsIgnoreCase(contentType.getBaseType())) ||
-                                (parts.html == null && "text/html".equalsIgnoreCase(contentType.getBaseType())))) {
-                    if ("text/html".equalsIgnoreCase(contentType.getBaseType()))
-                        parts.html = part;
-                    else
-                        parts.plain = part;
+                if (!Part.ATTACHMENT.equalsIgnoreCase(disposition) && TextUtils.isEmpty(filename)) {
+                    if ("text/plain".equalsIgnoreCase(contentType.getBaseType()))
+                        parts.plain.add(part);
+                    else if ("text/html".equalsIgnoreCase(contentType.getBaseType()))
+                        parts.html.add(part);
                 } else {
                     AttachmentPart apart = new AttachmentPart();
                     apart.disposition = disposition;